The present invention is related to a method and apparatus for making tubular composite articles, such as an acoustic liner for an aircraft nacelle.
An acoustic inlet barrel for a nacelle inlet may comprise a number of layers, including a perforated inner skin, an acoustic core, and an impervious outer skin. Typically, the inner skin is formed from sectors that are bolted together at axially extending seams. Ideally, however, the perforated skin has no internal seams or other features which may degrade the acoustic performance of the barrel.
U.S. Pat. No. 7,125,237 discloses a tool for molding an air intake, and more specifically for forming a one-piece inner skin having no internal seams. The tool comprises a mandrel having four arcuate sectors, a fixed sector that does not move during normal operation to the tool, two movable articulated sectors each hingedly connected to either side of the first sector; and a movable key sector which is independent from the other sectors and insertable between the articulated sectors. By virtue of the hinges, the articulated sectors remain connected to the fixed sector and cannot be separated therefrom. Locks are provided to secure the key sector to the articulated sectors. When in the molding position, the four sectors together define, by their external surfaces, a continuous surface corresponding to the internal surface of an air intake. A control device, disconnectable from the mandrel, may be used to adjust the movable sectors between a molding position and an non-molding position.
U.S. Published Patent Application No. 2007/0062022 discloses a tool for making a composite tubular structure. The tool includes a base on which are mounted a plurality of sectors, each sector having an outer panel provided with a predetermined shaped surface. The predetermined shaped surface corresponds to a portion of the contour of the tubular structure to be formed. At least one of the sectors is fixed relative to the base while the remaining sectors are movable in a radial direction and separable from all the other sectors. The sectors are provided with air bearings to facilitate movement along a radial direction. Splice plates are used to form a joint between the outer panels of adjacent sectors.